


Half Light

by lovedsammy



Category: Supernatural
Genre: Canon Divergence, M/M, Post-Episode: s14e13 Lebanon, Post-Episode: s15e08 Our Father Who Aren't in Heaven, Spec for post-episode s15e09
Language: English
Status: Completed
Published: 2020-01-05
Updated: 2020-01-05
Packaged: 2021-02-27 14:27:56
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,958
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22128709
Author URL: https://archiveofourown.org/users/lovedsammy/pseuds/lovedsammy
Summary: Canon divergent after 14.13, 15.08, and 15.09. After Sam uses his blood to banish the past, alternate timeline Castiel ("Lebanon") away, the warrior of Heaven is out for revenge. Chuck decides to use this other version of Castiel to torment Sam and Castiel further. But to save Sam, Castiel is faced with an impossible choice.
Relationships: Castiel/Sam Winchester
Comments: 3
Kudos: 35





	Half Light

**Author's Note:**

  * For [Avalonsilver](https://archiveofourown.org/gifts?recipient=Avalonsilver).



> This is a gift for @AvalonSilver. 
> 
> Basically, Chuck is a giant dick who wants to use the past Castiel to affect the current Sam and Cas and mess with them further. This is pre-established Sastiel (kinda; they’re figuring things out!), and takes place after 15.09. So kind of spoilery if you don’t know anything about the upcoming ep (hint: Sam is stuck with Chuck. This fic takes place after he gets away from him). 
> 
> (I totally listened to ‘Half Light’ by Banners during this btw, just fyi!)

Castiel lands like a fiery meteor upon the earth, dumped on the ground in an unceremonious heap. It’s undignified for an angel, he thinks, completely unbecoming. The first thing he registers is annoyance at the current state of his vessel. The clothing and hair is in disarray, and he smells of smoke. The next is righteous anger that the insignificant little human that was Sam Winchester had caused this. Castiel had only heard of him up until now, the boy with the demon blood. In some way, the angel guesses he’d been somewhat fascinated with the idea of the man who’d been born to become Lucifer’s true vessel. Meeting him had dissolved that fascination all together. The boy had no idea of his place. He’d used his tainted blood to send Castiel away, had weaponized it against Heaven and all it stood for. Zachariah would not be pleased, were he still alive. But he wasn’t, because Sam Winchester had killed him. 

The boy was going to be a bigger problem than he was worth. He had somehow disrupted the natural timeline and caused the deaths of angels with seemingly no regard for the consequences. So Castiel would make him understand, make him pay for the transgressions he’d committed against Heaven. He’d make Sam Winchester revere him, bow to him, and learn his place before he died. 

And if Dean Winchester tried to interfere, well - he’d learn, too. Heaven needed Dean alive and cooperative - they never said anything about unharmed.

Castiel searches for Sam’s current location, fixating on his presence, and detects it about 1,568 miles from where he is.

He takes off in a rapid flap of wings. 

-

Sam needed some fresh air. 

After escaping Chuck’s clutches, his brother was holding his hand a little too tightly when it came to readmission into the outside world. They hadn’t gone out for over a week, and if Sam tried to go for a run, it was always with Dean - or Cas, at Dean’s request - accompanying him. It was incredibly frustrating, the constant chaperoning. But Sam understood the reason for Dean’s current bout of overprotectiveness – he was worried about Chuck nabbing him again. But it wasn’t like Chuck couldn’t get into the bunker and haul Sam off from there if he’d really wanted to. And Sam couldn’t just stay locked up inside forever.

“I need to get out, Dean,” He’d said, exasperated, when he brought the issue up to his brother. “We all do. God’s not gonna stop just because we’re hibernating inside. If he wants to get at me, he’s gonna get at me. I’m done hiding. I’m going for a grocery run, because frankly, man, I need some actual food and not the junk we’ve been gorging on all week.”

Cas had looked up from the book he was skimming through. “Sam’s right, Dean,” He agreed. “He can’t stay locked up in here. Neither can you. I can go with him, if that makes you feel better.”

Sam could tell that Dean wasn’t fully comfortable with the idea, but after a long moment, he’d nodded. “Yeah, all right,” He relented. “I’m sorry, Sammy, for breathing down your neck. You’re right. I know it’s stupid. It’s just… let Cas go with you, okay? Please? Just for now, just until…” 

Sam sighed, but the extent of Dean’s concern admittedly made his heart swell. “Okay, yeah,” He’d agreed. He enjoyed Cas’s company, and wouldn’t mind him tagging along, if even just to appease Dean. So he’d nodded at Cas, who’d jerked up instantly and come over to his side. 

“We’ll be back before you know it,” Sam had assured his brother, patting him comfortingly on the shoulder.

\- 

It wasn’t often that Sam kept the windows rolled down when he drove, but tonight, he does. He breathes in the mild night air, inhaling leisurely. It feels refreshing after the long period inside. Cas glances over at him, lips twitching. 

“It’s about to rain,” The angel says conversationally. “I can taste it.” 

Sam laughs. “Really? And what does rain taste like to an angel? For me, it just tastes like water.”

Cas hums, thinking it over. “It’s hard to describe. It has a very strong earthy taste. Not like dirt, but… if air had a smell to it. It’s atmospheric, a mixture of gases that you are unable to taste, much less identify. Your mind recognizes it as water because it is unable to reach the capacity for beyond that.”

“Huh,” Sam says, intrigued.

He always learned so many interesting things when Cas was around, like the difference in biology between a human and an angel, for instance. Dean made fun of them for the late night class sessions, calling it ‘getting their geek on.’ Sam and Cas would roll their eyes simultaneously, and then head off hand in hand ,just to annoy Dean, to Sam’s room to binge more Netflix. The affronted look they got from Dean made it worth it every time. 

They finally arrive at the grocery store and get various breakfast, lunch, and dinner items, plus pie for Dean. It’s as he’s paying for the purchase that Sam gets the first inclination that something isn’t right - he feels like he’s being watched. A chill goes up his spine and he blinks, looking around, startled. Cas gives him an inquisitive look, but Sam just smiles at him. He was probably just being paranoid. Perhaps subconsciously, Sam on some level was worried about Chuck, too. _Thanks, Dean,_ he thinks wryly. _It’s contagious._

When they enter back out to the parking lot, the sensation is there again, stronger than before. Sam shakes his head as if to clear it, coming to an abrupt stop. No, something was definitely…. 

“Sam? What is it?” 

“I don’t know,” Sam murmurs. “I keep thinking…there’s someone. It feels like….” He trails off, looking at Cas.

Cas is instantly on alert. “Is it Chuck?” 

“I don’t know, I…” 

A sudden blast erupts around them and Castiel goes flying half-way across the parking lot, ejected high into the air before landing loud and painfully onto the hood of a car.

“Cas!” 

Sam makes to run to him, when a figure manifests before him and Sam’s stomach lurches. “W-What…?” 

It’s… Castiel. 

Sam’s confused beyond all hell. He opens his mouth to speak when Cas quickly seizes him, pinning him against the car with a hand clamped around his throat. Sam squirms under the pressure, trying to get free.

“Cas? What the hell?” 

“Be silent.” The angel snarls. “Heaven has allowed you to exist, Sam Winchester, when we could reduce you to dust whenever we should choose. You are an abomination on the highest level, just as Lucifer.” He leans forward, closer to Sam, and sniffs. “You reek of it, the blood that Azazel has tainted you with. Your soul itself is smeared.” 

Sam’s choking on the painful grip, not understanding what’s happening, why Castiel is attacking him, or saying such things. The angel uses his other hand to pull at Sam’s hair, forcing his head up. 

“You are going to learn to show me respect, abomination. You are going to grovel at my feet, at Heaven’s feet, and beg for forgiveness. I will embed the price of your sin into you as you beg for death.” He removes the hand from Sam’s throat only to redirect it into the younger Winchester’s face. The back of Sam’s head collides with the side window, and he groans loudly. Castiel continues the assault, dragging Sam forward and shoving him head first through the windshield, pieces of glass flying everywhere, jagged edges cutting into Sam’s flesh. He falls to the pavement with a gasp, trying and failing to fight the angel off of him. 

“Cas, stop,” He says weakly, holding up his hands. “It’s me.” He remembers now. This was the Castiel that he and Dean faced in the alternate timeline, when their father had returned. But they’d fixed that, hadn’t they? Sam had banished him… 

“My name is Castiel, and you will address me as such.” Castiel growls, standing over him. “How dare you refer to me with such a condescending name, speaking of me with familiarly, as if we know each other.” 

“We do,” Sam insists around a mouthful of blood. “Cas, please, you’re my friend, you’re –” 

“Sam!”

Sam raises his head to see Castiel, the real Castiel, his friend and whatever they were now, running towards him, eyes wide and angel blade clutched in his hand. 

The other Castiel stares at him in shock. “You… you’re….?” 

“I’m Castiel,” The real Cas snaps. “As are you. We are one and the same. I’ve heard of you. You’re me, but from the past. You’re who I was before I met the incredible man that you seem to take pleasure in manhandling. I don’t know how you got here, or what you’ve been led to believe, but it’s a lie. Sam is my friend, and I do not appreciate the harm you are dealing to him. So let him go.” He brandishes the blade threateningly, taking a step forward. “Now.” 

The other Cas’s eyes narrow. “What has happened to you?” He demands. “You have befriended the taint of Heaven? You offer him protection? How far have you fallen? You and I are not the same. The mission, our mission, was to stop Sam Winchester, and offer Dean Winchester the sanctuary of Heaven. Our mission was to inspire the brothers Winchester to start the Apocalypse, and become the Vessels.” 

“That mission was a farce,” Castiel replies tersely. “It was orchestrated by Heaven, not because our Father commanded it. Castiel, you should know this. How many times have you, have I, have we questioned Heaven’s objectives? How many times have we been reprogrammed by our superiors for doing so?” 

The other Cas looks confused now. “Reprogrammed?” 

“Yes,” Castiel says impatiently. “Your head, just as mine, has been washed clean over and over. Do you know why? Because of our love for humanity. Our love for the man before you that you insist on submitting to your will. You do not know him, Castiel, not truly. Not yet. But you will. And who you are now is who I once was. Who I am now is who you will become.” 

Perplexed, the alternate Castiel’s eyebrows furrow, and the pressure on Sam’s hair decreases slightly. “Heaven’s will is absolute. I don’t understand.” 

“I know you don’t,” Castiel says almost gently, beginning to approach further. “Believe me, I didn’t for a long time. But you have been deceived. I am not your enemy. And neither is Sam Winchester.” 

Sam watches the pair of them, hardly daring to breathe. He didn’t remember past Castiel being this aggressive about Heaven’s commandments. Something was off, more than the other Cas being brainwashed to obey without contention. Even while it was true that the other Cas had beat the shit out of him, it’d been robotic and without any feelings involved. He wants to voice this, but as he looks up at the alternate version of his friend, the hateful look he gets makes him go pale. 

The grip on his head is back in full force, and Sam cries out. The other Castiel’s eyes are aglow in blue. “No,” The angel growls. “Sam Winchester is Heaven’s enemy, and therefore he is mine. He has to die here and now. Stand down, and I may choose to let you continue existing in this current time.”

“No!” Terror grips Castiel and he surges forward, ready to attack. 

“Ah, don’t you just love crossovers?”

The new voice makes everyone pause, and Sam’s heart stutters. Oh no…. 

“Chuck.” Cas declares, eyes flashing dangerously. “What are you doing here?” 

Chuck raises a hand. “Relax. Just catching the newest episode of my favorite show. And oh man, what a show! Two Castiel’s? Sam Winchester caught between them? Not exactly my cup of tea, this would be more up Becky’s alley for a slash fic, but, hey! When life gives you lemons, right?” He smiles wide, nodding at the other Cas. “Well, what are you waiting for? Kill him already.”

The other Castiel hauls Sam painfully up to his knees, going for his throat again, the force of his grip so strong that it makes Sam’s eyes almost bulge out of his head. 

“N-No..” 

“Don’t you dare!” Cas yells, striding forward again. “Don’t make me kill you. Let him go!” 

“Yeah, that’s not gonna happen,” Chuck says easily, amused. “There’s no point trying to reason with this Castiel. See, I made him for this very purpose. I kind of played around with his machinery a bit. This version of you is not going to protest against Heaven’s orders. There’s no crack in his chassis. This Castiel will do whatever I ask him to. He has no emotional attachment to Sam, unlike you.” 

Sam stares blearily at him through his fringe. Of course he was behind this. Blood is pouring from his mouth and nose, and he thinks his arm may be broken. “Cas,” He wheezes. 

The fear in Sam’s voice and the fact that he’s turning a dark shade of red makes Cas finally act. He closes his eyes, hating what he must do, but knowing there was no choice, not if it meant saving Sam. “I’m sorry.” He plunges the angel blade as far as it will go into the other Castiel. 

But there’s no reaction. No sign of pain, nor blinding light. He was still standing, still alive. But it’s effective - the grip on Sam lessens slightly, enough that he can get some oxygen back into his aching lungs. The other Cas twitches his wrist, flinging Castiel backward and back to the ground again. 

“Killing him isn’t gonna work,” Chuck continues as if he hadn’t been interrupted. “There’s only one way to stop him, Cas. You need to take from him what Metatron once took from you. Then you can save Sam. But!” He holds up a finger, smirking, as Cas clambors back to his feet. “Before you decide to spring forward to help him, you may want to think about this. To save Sam, you’ll need to take the other you’s grace. But if you take his grace… there’s going to be some, ah, adverse side effects, we should say. You will forget Sam. You’ll forget Dean. You’ll forget your son, Jack. You’ll lose them, all memory of them, and who you are now. Tell me, is saving Sam really worth that to you?” 

Castiel pauses as Chuck’s words sink in, feeling helpless. He didn’t want to forget them, his friends, or Jack. He didn’t want to forget Sam, and his love for him. He didn’t want to lose himself, to go back to being the unfeeling warrior standing before him. Everything he was now was because of Sam and Dean, and his love for them. 

“Cas,” Sam calls out urgently. “Cas, don’t do it. Don’t lose yourself, not for me.”

Castiel looks at Sam and can hardly believe that he’s real. Such a beautiful creature this man was, so loving and selfless and irreplaceable. The world would never recover from losing Sam Winchester. There was no contender. Sam could never ask Castiel to sacrifice him for the sake of himself. 

The decision was made before Chuck had even really given him the choice. He’d choose Sam every time. Cas can tell that Sam knows, sees the weight of the realization on the younger Winchester’s face, the way his eyes widen. 

“No. No, no, Cas, don’t.” 

“Didn’t I tell you once before, Sam?” Cas smiles resolutely. “Nothing is worth losing you.” 

Effortlessly, he brings the blade forward and swings. It glides horizontally across the other Castiel’s throat, slitting it in half. Cas doesn’t wait to watch the life leave his counterpart’s eyes before he opens his mouth and swallows the brilliant white glow whole. 

He thinks he hears Chuck laughing behind him, but ignores it. The sensation of the grace fills him up, and he can feel them slipping - his memories. His emotions. He tries to cling to them still, those precious fleeting moments in his long, long life. It’s terrifying, the way they start to slip away. “No, no,” He whispers. “Come back. Please, don’t…” 

“Cas… Cas…” 

Cas feels Sam’s hands on his face, sees his brilliant hazel eyes staring back at him. Sam looks terrified, guilty, heartbroken. Cas wishes to calm him, even in the depth of his own fear. He raises a finger to swipe the tear on Sam’s cheek away. 

“It’s all right, Sam,” Cas tells him. 

Sam shakes his head. An instant later, he’s pressing his lips to Castiel’s, and the connection it creates is beautiful. If this is how he’s going to forget the man that he loves, then perhaps it’s not so bad. Cas waits, but nothing’s happening. It all stops. Sam is still kissing him, more passionately now, and Cas lets himself get lost in the feeling of Sam’s lips on his own. The memories that Castiel could feel slipping before are suddenly at the forefront of his mind. 

“No!” Chuck shouts, drawing both of their attention enough to break the kiss. “Damn it, this wasn’t supposed to happen.” He looks furious, put out, and vanishes into the night.

Sam whips his head around to look back at Cas just as the sky opens up and rain descends upon them. “Cas? Cas, are you…?”

“I’m fine,” Cas says in disbelief. “I still remember, Sam. I remember everything.” He presses two experimental fingers to Sam’s forehead and easily heals the damage. “And I’m fully me again.”

Sam laughs in pure elation, resting his forehead against Cas’s as the rain seeps under their clothes and onto their skin. 


End file.
